From 398180f93cf3c7bb0ee3f512b139ad01843f3ddf Mon Sep 17 00:00:00 2001 From: Sean Christopherson Date: Mon, 10 Nov 2025 13:24:53 -0800 Subject: [PATCH] KVM: TDX: Use struct_size to simplify tdx_get_capabilities() Use struct_size() instead of manually calculating the number of bytes to allocate for 'caps', including the nested flexible array, and copy all of 'caps' to user space with a single copy_to_user() call (thanks to the full size being provided by struct_size()). Signed-off-by: Thorsten Blum Tested-by: Rick Edgecombe Link: https://patch.msgid.link/20251017213914.167301-1-thorsten.blum@linux.dev [sean: separate from swap of get_user() vs. kzalloc() ordering] Signed-off-by: Sean Christopherson --- arch/x86/kvm/vmx/tdx.c | 13 ++++--------- 1 file changed, 4 insertions(+), 9 deletions(-) diff --git a/arch/x86/kvm/vmx/tdx.c b/arch/x86/kvm/vmx/tdx.c index cc751c0884766..a940a54ca5933 100644 --- a/arch/x86/kvm/vmx/tdx.c +++ b/arch/x86/kvm/vmx/tdx.c @@ -2231,9 +2231,8 @@ static int tdx_get_capabilities(struct kvm_tdx_cmd *cmd) if (nr_user_entries < td_conf->num_cpuid_config) return -E2BIG; - caps = kzalloc(sizeof(*caps) + - sizeof(struct kvm_cpuid_entry2) * td_conf->num_cpuid_config, - GFP_KERNEL); + caps = kzalloc(struct_size(caps, cpuid.entries, + td_conf->num_cpuid_config), GFP_KERNEL); if (!caps) return -ENOMEM; @@ -2241,16 +2240,12 @@ static int tdx_get_capabilities(struct kvm_tdx_cmd *cmd) if (ret) goto out; - if (copy_to_user(user_caps, caps, sizeof(*caps))) { + if (copy_to_user(user_caps, caps, struct_size(caps, cpuid.entries, + caps->cpuid.nent))) { ret = -EFAULT; goto out; } - if (copy_to_user(user_caps->cpuid.entries, caps->cpuid.entries, - caps->cpuid.nent * - sizeof(caps->cpuid.entries[0]))) - ret = -EFAULT; - out: /* kfree() accepts NULL. */ kfree(caps); -- 2.47.3